Cast Stainless Steel Research Articles

The effect of low pH in erosion-corrosion resistance of high chromium cast irons and stainless steels

Corrosive wear is a form of material degradation that is known to occur on equipment and components that handle suspended solids in aqueous solutions. This surface deterioration process is generally enhanced when the fluids contain chlorides that are acidic in nature. Such environments are encountered in many applications, one such example being the minerals processing industry.High chromium white cast irons are widely used in many engineering applications as they extend the service life beyond that of stainless steels. In this work, the corrosive wear of austenitic stainless steel UNS S31600 and martensitic stainless steel UNS S42000 are compared with high chromium white cast irons (27WCI and 37WCI) by using a submerged jet technique at perpendicular incidence. The testing medium consisted of 3.5% NaCl liquid solution (pH 7 and pH 3) with suspended silica sand particles. The post-test methodology characterised the material loss within the directly impinged zone and turbulent zone where abrasive damage is involved. In neutral conditions, the presence of chromium carbides in white cast irons provided benefits, whilst in the acidic conditions, the austenitic structured materials (for stainless steels and white cast irons) suffered lower overall material loss compared with the martensitic structured materials.

Combination of Electrochemical Noise and Acoustic Emission for Analysis of the Pitting Corrosion Behavior of an Austenitic Stainless Cast Steel

The pitting corrosion behavior of a high alloy cast steel is analyzed in a sodium chloride solution by combination of the electrochemical noise technique and the acoustic emission (AE) method. Four corrosion states are identified on the steel surface after the 70 h noise measurement test. The simultaneously monitored AE exhibits two types of acoustic signals. The first type of AE events is attributed to the local passive oxide breakdown and the pit initiation process and the second type of AE events is related to the subsequent associated hydrogen gas bubble evolution.

Mechanical properties and kinetics of thermally aged Z3CN20.09M cast duplex stainless steel

Cast stainless steels used in nuclear power plants suffer from fracture toughness losses owing to thermal aging after long-term service at temperatures ranging from 280–320°C. To study the thermal aging embrittlement of Z3CN20.09M duplex stainless steel produced in China, accelerated thermal aging experiments were carried out at 350, 380, and 400°C for up to 10000 h. Microhardness and Charpy impact energies were measured at different aging times. The microhardness of ferrite increased drastically over the initial aging time of 2000 h at 380 and 400°C and then slowly reached HV0.01 560. In contrast to this observed change in microhardness, Charpy impact energies sharply decreased after initial aging and then gradually reached a minimum value. Taking the microhardness of the ferrite phase as the parameter describing the thermal kinetics of the stainless steel samples, the activation energy of thermal aging was calculated to be 51 kJ/mol. Correlations between the thermal aging parameter, P, and ferrite microhardness and between P and Charpy impact energy were also analyzed. The results showed that the activation energy calculated from the ferrite microhardness is much more reasonable than that obtained using other parameters, such as chemical composition and impact energy.

The study on the measurement accuracy of non-steady state temperature field under different emissivity using infrared thermal image

In this paper, the temperature measurement accuracy of infrared thermal image under different emissivity is studied. Firstly, according to the formula of infrared temperature measurement, the influence of the object surface emissivity on the measurement accuracy of infrared thermal image is analyzed. The factors affecting the emissivity of the object are found. Secondly, the limitation of classical emissivity calculation method in infrared temperature measurement is explained. Thirdly, a model for improving the temperature accuracy of the non-steady state temperature field based on the emissivity of the infrared image is obtained, and the theoretical formula is obtained. Finally, three experiments of cast iron and stainless steel are carried out. The correctness and feasibility of this method is verified by the experimental results.

Microstructural bandings evolution behavior and their effects on microstructure and mechanical property of super-austenitic stainless steel

Bands were cut from surface and center sections (denoted as SS and CS, respectively) from a super-austenitic stainless steel cast slab, and were hot rolled to be 3 mm thick plates under the same conditions. It was found that the SS hot-rolled plate possesses different microstructural bandings (MSBs) from those in the CS plate. Formation mechanisms of MSBs and precipitates during hot rolling and their evolution behavior during solution treatments (1000–1150 ℃ for 30 min) were investigated. The results show that the SS plate has slight MSBs with no precipitates, while the CS plate has high density of MSBs consisted of massive σ phases. The MSBs in SS and CS plates were found to be vanished after solution treatments at 1000 ℃ and 1100 ℃, respectively. Also, length fractions of low-ΣCSL boundaries of Σ3, Σ9 and Σ27 in both SS and CS plates were observed to increase and then decrease with increasing temperatures. The MSBs could have affected the evolution of grain boundaries, and changed the length ratio of CSL boundaries to the total grain boundaries. Numerous zonal structures composed of fine grains were observed in CS plates after solution treatment. Precipitates inside the MSBs could retard the boundaries movement during recrystallization to refine the grain. Tensile tests indicate that the strength of hot-rolled and solution-treated CS plates was higher than that of SS plates by 2–7%, and the elongation reduced by 2–5%. The main reasons were that the smaller average grain sizes and the precipitates in MSBs of CS plates enhanced the strength but the precipitates deteriorated the elongation.

Retrospective analysis of corrosion and ion release from retrieved cast stainless steel tibia plateau leveling osteotomy plates in dogs with and without peri-implant osteosarcoma.

OBJECTIVE To evaluate and compare surface and cross-sectional structure as well as localized electrochemical corrosion and ion release for cast stainless steel (SS) tibia plateau leveling osteotomy (TPLO) plates retrieved from dogs with and without osteosarcoma (OSA) and to compare these findings with similar variables for forged SS TPLO plates retrieved from dogs. SAMPLE 47 TPLO plates explanted from 45 client-owned dogs (22 cast plates from dogs with OSA, 22 cast plates from dogs without OSA, and 3 forged plates from dogs without OSA). PROCEDURES Histologic evaluations of tissue samples collected from implant sites at the time of plate retrieval were performed to confirm implant site tumor status of each dog. Surfaces and metallographic cross sections of retrieved plates were examined, and the microcell technique was used to obtain local electrochemical corrosion and ion release measurements. RESULTS Findings indicated that all cast SS plates demonstrated high spatial variability of their electrochemical surface properties and inhomogeneous superficial and cross-sectional composition, compared with forged plates. Greater metal ion release was observed in cast plates than in forged plates and in cast plates from dogs with OSA than in cast or forged from dogs without OSA. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that accumulation of metal ions from implants could be a trigger for neoplastic transformation in neighboring cells. Metal ion release caused by corrosion of implants that do not comply with recommended standards of the American Society for Testing and Materials International or the International Organization for Standardization could potentially place patients at increased risk of tumor development.

Definition of range of open applications for massive nodes in the stainless steel castings

The main purpose of the app is receiving a suitable casting without shrinkage cavities and porosity. In general, the pattern of formation of these defects can be represented as follows: in a very short period of time on the casting surface and formed a crust of hardened alloy, which determines the outer contour of the casting; reduction of volume of the liquid metal inside the formed solid crust ahead of volumetric shrinkage, the most rigid sheath; in the absence of receipt of molten metal, which compensates the reduction of volume, voids are formed, called sinks, the size of which depends on the properties of the alloy, the temperature of the overheating and its original volume. The aim of this work is to study the influence of size, shape and location of applications on the formation of porosity in the casting behind the massive knots out of stainless steel. During the work was designed by the two most common type the location of the massive object on the wall of the casting. The first stage was simulated the crystallization process of these knots in the free state without application. The presence of porosity was evaluated according to the Niyama criterion. The next stage was a relatively action works, designed by the most common means of calculation, and standard shapes and sizes. For the analysis of efficiency was analyzed the distribution of temperature fields and the presence of porosity. The application must meet the following basic requirements: be sufficient to compensate for the shrinkage of the alloy during solidification; later hardening the casting parts to which it is attached; have the configuration (to keep metal), which will provide a minimum cooling surface; area shrinkage should not go beyond the app and reach his neck.

On the origin of subgrain boundaries during conventional solidification of austenitic stainless steels

The origin of subgrain formation during conventional casting and solidification of stainless steels was studied using two austenitic stainless steels with 0 and 4 mass-% Al. Whereas the Al-free alloy showed no subgrain formation, the Al-added alloy developed a high density of subgrains separated by low-angle grain boundaries. The occurrence of subgrains in the Al-added alloy was justified by its ferritic mode of solidification as predicted by thermodynamic calculations and confirmed by dynamic scanning calorimetry measurements. The subgrains might be a consequence of the plastic deformation of soft primary ferrite dendrites by the fluid flow and their subsequent inheritance by the austenite. Alternatively, they might have been induced during the austenite formation from delta ferrite, most likely via a peritectic reaction. The absence of subgrains in the Al-free alloy was justified by its austenitic mode of solidification.

MANAURITE 36X

Abstract Manaurite 36X is cast stainless steel with a composition (26Cr-35Ni) that makes it resistant to both oxidizing and carburizing atmospheres at high temperatures. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as joining. Filing Code: SS-1286. Producer or source: Manoir Pîtres.

Assessment of Ductile, Brittle, and Fatigue Fractures of Metals Using Optical Coherence Tomography

Some forensic in situ investigations, such as those needed in transportation (for aviation, maritime, road, or rail accidents) or for parts working under harsh conditions (e.g., pipes or turbines) would benefit from a method/technique that distinguishes ductile from brittle fractures of metals—as material defects are one of the potential causes of incidents. Nowadays, the gold standard in material studies is represented by scanning electron microscopy (SEM). However, SEM instruments are large, expensive, time-consuming, and lab-based; hence, in situ measurements are impossible. To tackle these issues, we propose as an alternative, lower-cost, sufficiently high-resolution technique, Optical Coherence Tomography (OCT) to perform fracture analysis by obtaining the topography of metallic surfaces. Several metals have been considered in this study: low soft carbon steels, lamellar graphite cast iron, an antifriction alloy, high-quality rolled steel, stainless steel, and ductile cast iron. An in-house developed Swept Source (SS) OCT system, Master-Slave (MS) enhanced is used, and height profiles of the samples’ surfaces were generated. Two configurations were used: one where the dimension of the voxel was 1000 μm3 and a second one of 160 μm3—with a 10 μm and a 4 μm transversal resolution, respectively. These height profiles allowed for concluding that the carbon steel samples were subject to ductile fracture, while the cast iron and antifriction alloy samples were subjected to brittle fracture. The validation of OCT images has been made with SEM images obtained with a 4 nm resolution. Although the OCT images are of a much lower resolution than the SEM ones, we demonstrate that they are sufficiently good to obtain clear images of the grains of the metallic materials and thus to distinguish between ductile and brittle fractures—especially with the higher resolution MS/SS-OCT system. The investigation is finally extended to the most useful case of fatigue fracture of metals, and we demonstrate that OCT is able to replace SEM for such investigations as well.

Characterization of the high temperature oxidation behavior of iron based alloys used as exhaust manifolds

Nowadays engine capacities of vehicles spread in a wide range due to different vehicle power demands. Power density of engines affects exhaust gas and therefore exhaust gas temperature varies from 650 °C to 1000 °C in exhaust manifolds. Depending on the exhaust gas temperature, different types of iron based alloys are used as manifold materials such as ferritic ductile cast irons (GGG40, SiMo), austenitic ductile cast irons (Ni-resist D5S), ferritic cast stainless steels (ACIHK30, AISI 409) and austenitic cast stainless steels (CF8C). In this study high temperature oxidation behavior of different cast alloys used as exhaust manifold materials like, (i) GGG40 ferritic ductile cast iron, (ii) SiMo ferritic ductile cast iron (iii) AISI 409 ferritic cast stainless steel and (iv) CF8C austenitic cast stainless steel, were investigated.

Effect of sand concentration on erosive – corrosive wear behavior of chill cast aluminum – boron carbide composites

In the present investigation, the erosive – corrosive wear behavior of chill cast aluminum boron carbide composites have been studied in marine environment. The composites were fabricated by gravity die casting using vortex method. Metallic chill materials with different thermal conductivity (stainless steel, cast iron and copper) were used as mold materials. Silica sand of particle size 312 microns was used as erodent material. The experiments were performed at room temperature for a testing period of 3 hours at a speed of 900 rpm by varying the sand concentration from 10–50 wt. % in steps of 20 wt. %. From the present study it is noticed that, irrespective of the material the slurry erosive wear rate increases, as the quantity of the sand in the slurry increases. It is also noted that the copper chill cast composites exhibits greater wear resistance than the cast iron and stainless steel chill cast composites due to its fine grain structure obtained through faster cooling rate of the copper chill because of its high thermal conductivity. The study of the worn surface by scanning electron microscope reveals that the increase in the quantity of the sand in the slurry solution leads to greater damage to the exposed surface due to the rise in the extremity of the erosive – corrosive attack.

Effect of Angle of Impingement on Air Jet Erosion Wear Behavior of Chill Cast Aluminum-Boron Carbide Composites

In the present investigation, the effect of angle of impingement on the air jet erosion wear behavior of chill cast aluminum boron carbide composites have been studied under room temperature. Stir casting technique was employed for the development of the composites. Metallic materials like stainless steel, cast iron and copper with various thermal conductivities are used as end chills. The erodent material used was silica sand of 312 microns. All the tests were conducted with the erodent silica sand particles of grain size 312 µm at a standoff distance of 20 mm with a testing time of 5 minutes for 15°, 30°, 45° and 60° angles of impingement. The worn surface analysis was carried using scanning electron microscope to examine the mechanism of material removal process. From the obtained results, it is noticed that the weight loss of the samples increases with the increase in angle of impingement up to 45° and then decreases with further increase in the angle of impingement for a given standoff distance and testing time. However, for all the composite samples studied, the copper chill cast Al-B4C composites exhibit greater erosive wear resistance than the cast iron and stainless steel chill cast composites.

Determination of Combined Hardening Parameters to Simulate Deformation Behavior of C(T) Specimen under Cyclic Loading

Cyclic hardening rule is important to simulate deformation behaviors in low cycle fatigue analysis. Due to a complexity of cyclic hardening, it is hard to predict deformation of components accurately. Also, in the case of a cracked problem, severe deformation occurs in the region of crack front. To perform low cycle fatigue analysis and predict deformation behaviors, the type of cyclic hardening rule should be determined. In this study, the determination procedures of combined hardening parameters (Chaboche model) are described briefly and the effects of two parameters on deformation behavior are analyzed. Combined hardening parameters are determined from each hysteresis loop with different strain amplitudes. The experiment data from two different materials (SA312 TP316 stainless steel and CF8A cast austenite stainless steel) and two different load ratios (R=-0.5 and -0.1) are used for simulations. In addition, hysteresis loops from three strain amplitudes are used to explain how the parameters from different strain amplitudes can influence on deformations of cyclic C(T) simulation.

Применение инокулирующего модифицирования для повышения стойкости литого металла заготовок из нержавеющей стали к межкристаллитной коррозии

Применение инокулирующего модифицирования для повышения стойкости литого металла заготовок из нержавеющей стали к межкристаллитной коррозии

Study on three-dimensional simulation of ultrasonic wave propagation in statically cast stainless steel using numerical solidified microstructure model

Study on three-dimensional simulation of ultrasonic wave propagation in statically cast stainless steel using numerical solidified microstructure model

Numerical Simulation of Thermal Ageing Effect on Fracture Behavior for CF8A Cast Stainless Steels under Very Low Cyclic Loading Conditions

In this paper, a method to predict the fracture toughness of thermally-aged CF8A under cyclic loading condition is proposed. The FE damage model based on multi-axial fracture strain energy is applied for the prediction. The predicted results are compared with the experimental data of C(T) specimens. The multi-axial fracture strain energy of unaged CF8A can be obtained from tensile and C(T) data under monotonic loading condition. Then, the multi-axial fracture strain energy of aged CF8A can be determined by introducing the concept of thermal ageing constant “C”. From the determined multi-axial fracture strain energy of aged CF8A, the fracture toughness of aged CF8A is predicted under monotonic and cyclic loading condition. The predicted results show good agreement with experimental data.

Study on Deleterious Phases Precipitation on Super Duplex Stainless Steel Grade 6A- ASTM A890

Production of Super Duplex Stainless Steel casting sometimes becomes difficult due to development of cracks, particularly in big casting. These cracks can be found during various stages of production. For this steel, deleterious precipitation of phases like sigma, chi, secondary austenite, various carbides and nitrides takes place at different temperature and time and they affect the properties of the steel. Among all such precipitates, sigma is most harmful. It has poor notch toughness and hard and brittle. They are potential source of crack development in the casting. In this study, occurrence of such precipitates examined by keeping the steel in critical temperature range and for varying time. At 800 & 900°C, ferrite diminishes with ageing time and transform to sigma and other harmful phases which sharply reduces toughness and ductility of steel. Sigma precipitates by holding the sample even for 1minute at 800°C. Faster cooling rate, good agitation of bath and minimum quenching time are some of the steps which reduces casting crack during heat treatment process.

Mn, Si and Ti in cast stainless steel at elevated temperature

ABSTRACTACI HH II is an austenitic castable stainless steel for high-temperature applications such as grates in a Grate-Kiln indurator. Eight different alloy compositions have been used to evaluate the oxide formation and the microstructural evolution during an isothermal heat treatment at 800°C with a holding time of 200 h in an atmosphere containing 20% O2–N2. Residual ferrite is transformed into sigma phase during the heat treatment while secondary carbides are precipitated in the austenite. Silicon will form a thinner oxide but will reduce its adherence to the steel. Additions of Ti are beneficial for the properties of the oxide layer as the oxide is well adherent and thinner, while additions of Mn increase the growth rate of the oxide and enhance the risk of growth stresses in the oxide. It is proposed that by combing the beneficial effects of both Ti and Si it is possible to suppress the malign effects of Mn additions.

Influence of Heat Treatment on Interface Structure of Stainless Steel/Gray Iron Bimetallic Layered Castings

The present study is undertaken to investigate the influence of annealing and normalizing heat treatment on the bimetallic interface microstructures of 304 stainless steel and gray cast iron. The current work is aim to control the bimetal interface microstructures by different types of heat treatment processes to improve performance of the bimetallic castings performance. For low temperature annealing, specimens are heated to 760 0C for 60 min in an electrical heating furnace. For high temperature annealing and normalizing, specimens are heated to 920 0C for 120 and 240 min. A different interface structures are obained for all heat treated samples. Annealing and normalizing induce a significant effect on the diffusion of C and Cr elements and slightly effect on the diffusion of Ni element. Thickness of interface layer 1 (austenite + carbide) increases by increasingthe annealing temperature.